Emphysema is defined as a destruction of alveolar
walls and consequent enlargement of air spaces.The main known cause is cigarette smoke, but a few cases
are caused by an inherited lack of the enzyme
alpha-1-antitrypsin.
Emphysema may involve different parts of the lung for reasons that
are not clear. In the severe forms, all are associated with
difficulty breathing (shortness of breath). The expiratory phase of
breathing is prolonged and may be accompanied by audible wheeze.

Emphysema

This lung was dried and sliced. It shows
marked emphysema, more severe at the top. Much tissue has
been destroyed and the lung is larger than normal.

Closs-up of
Emphysema

A close-up of the mid lung shows that some
emphysematous holes are still surrounded by normal lung. The
destroyed portion is around the small airways in this
case.

Find 3 emphysematous holes.
Remember to click on
them to see if you are right.

Emphysematous change can be
likened to Swiss cheese. The normal lung has a uniform
cheddar cheese appearance. The Swiss cheese change comes
about from enzymes that are activated by cigarette smoke.
These enzymes eat away at the alveolar walls and cause
holes.

Bullous Emphysema

This lung shows an example of localized,
bullous emphysema (bulla = enlarged air space >1 cm in
diameter). The emphysema is located at the top of the lung.
Note that the tissue not involved in the emphysema appears
almost normal in this case.

Find and outline the
bulla.

Giant bullous emphysema:
Giant bullae consume more than 1/3 of a lung
radiographically. The remainder of the lung may be normal, as shown
here. Isolated bullae with normal lung may be associated with few
symptoms until bullae enlarge sufficiently to compress normal lung
and interfere with function. Just as in diffuse emphysema, the
localized cysts do not empty well on expiration. Most are caused by
cigarette smoking. Radiographic studies can distinguish bullae with
normal lung from bullae with diffuse emphysema. Patients with bullae
in otherwise normal lung are a subset of patients who may benefit
from excision of the bullae.